One more thing to add some color to this random vs actual initialization issue. The actual MSE Loss is NOT a good proxy for how "good it looks to the human eye". Here's an interesting test. I tried to do Dr. Seuss style painting on my dog image.

So the actual image gets to a better place. But now, lets look at about the same MSE place in both. Here's what the painted image starting from random conditions looks like after 30 iterations, loss = 1904.

Not great.

Here's what the actual initialization looks like after 13 iterations. Note that the loss here is 2069... technically worse than the random one after 30 iterations.

I think this is a better painted image... Seems like the loss is not capturing what I deem to be a good painting.Pretty cool.

@rachel, great! Please do. It has been a game changer for me. Perhaps, if it fits in somewhere it would be interesting to also cover ctables. So far, though, I used carrays. For the time being the most useful (IMHO) link to bcolz documentation is this tutorial

Building a new box. Getting xgboost error. Using Ubuntu 16.10 (with anaconda3/python3.6). Any suggestions?

import xgboost/home/gaurav/anaconda3/lib/python3.6/site-packages/sklearn/cross_validation.py:44: DeprecationWarning: This module was deprecated in version 0.18 in favor of the model_selection module into which all the refactored classes and functions are moved. Also note that the interface of the new CV iterators are different from that of this module. This module will be removed in 0.20. "This module will be removed in 0.20.", DeprecationWarning)Traceback (most recent call last): File "", line 1, in File "/home/gaurav/anaconda3/lib/python3.6/site-packages/xgboost/__init__.py", line 11, in from .core import DMatrix, Booster File "/home/gaurav/anaconda3/lib/python3.6/site-packages/xgboost/core.py", line 112, in LIB = _loadlib() File "/home/gaurav/anaconda3/lib/python3.6/site-packages/xgboost/core.py", line 106, in loadlib lib = ctypes.cdll.LoadLibrary(lib_path[0]) File "/home/gaurav/anaconda3/lib/python3.6/ctypes/__init__.py", line 422, in LoadLibrary return self._dlltype(name) File "/home/gaurav/anaconda3/lib/python3.6/ctypes/__init__.py", line 344, in init self.handle = _dlopen(self.name, mode)OSError: /home/gaurav/anaconda3/lib/python3.6/site-packages/scipy/sparse/../../../../libstdc++.so.6: version `GLIBCXX_3.4.22' not found (required by /home/gaurav/anaconda3/lib/python3.6/site-packages/xgboost/./lib/libxgboost.so)